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Cheers for the tips! Found the bar had a small paint chip during transit... Thanks NZ Couriers. So I decided to touch up the paint with some spare Legacy silver and clear coat. Might try install this weekend.
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yes ill post the dyno sheet hopefully tommorow. Yeah 4 more psi only got me 13kw lol
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Have you got a dyno sheet for it? Seems like a heap of boost to make that power even with knock. Chris knows better than all of us, but surely that figure could have been achieved at a lower boost level which could have meant a somewhat cooler charge allowing more timing. Mine gets 190 with a peak of 17psi and is infact down to more like 14psi at that point.
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Thicker HG will affect both CR and quench, you're increasing the volume of the combustion chamber. Yep even a lot of aftermarket Subaru pistons are a (rounded) square bowl. @Inked it means you're effectively running a sliiiightly higher compression ratio, so it just means you will, in theory, require less boost to generate the same pressure on the power stroke.
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@evowrx Though it was both, but that post was meant to be pretty generic. writing S*** to explain without lots of terms it is pretty long without pictures and I'm not saying I'm good at it or that it was complete. Plus aren't early Subaru pistons just cut with a square bowl and only the edge was flat, nothing as bad as Honda etc.
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Yeah, I definitely feel more torque earlier on in the rpm range and at some points higher up there are some decent power differences. Ill post charts up when I get my phone back.
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Doesnt switching the headgasket affect quench not c/r?
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Ok compression ratio the difference between volume or air in the cylinder when the piston is at the bottom. volume or air in the cylinder when the piston is at the top. say you have a 2L 4 cylinder boxer shocking I know each cylinder is 250cc when the piston is at the bottom. if that got compressed as the piston traveled up and the valves are closed so it can't escape it goes down to 25cc that would be 10:1 compression. anyway @boon is more technically accurate, but you get the idea.
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As a side note, the type of detonation/knock you're getting isn't dieseling (spontaneous explosive combustion of the contents of the cylinder due solely to compression) but when timing is added (advanced) the mixture is burning too quickly, or burning explosively (all at once instead of an advancing flame front), but the long and short of it is you're getting peak cylinder pressure before a couple of degrees after (I think it's just after that you want, but I've had a coupla wines...) TDC. This means that the explosion is fighting the rise of the piston initially instead of helping it to go down (across, yay Subaru) the cylinder. There's a variety of possible causes and it can be a bugger to track down; recently it seems that quite a few V7 motors have been prone to it. Current theories are excessive blowby causing loss of octane/knock resistance, and the exhaust valves floating combined with high exhaust backpressure allowing exhaust gasses to linger in the cylinder, causing increased cylinder temperature and increased chance of detonation.
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Oh my god. I think my brain brain just snapped a rod haha. Thank you for explaining this, it is interesting that myself & @Subru have had a similar experience with the detonation up top. I am feeling relieved to know that there are ways to counter this though. When a tuner says something like that to you I automatically thought the worst ha ha.
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190 is all good imo think my Rs did 190 with similar mods (I had old Rs hydraulic heads, non semi forged pistons, maxed at 17psi and had an engine that had seen abuse for a lot of its 260,000km life, also the td05 helped out) curious us about the early knocking though at least you know the tune you now have is SAFE so every time you redline it you know there's no damage happening that was my main worry before I had a tune
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Engineering explained... My brain just dies after one of his videos. His new videos full of graphs and equations im just like naah its easier to just watch some videos of cars having crashes.
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Ok you need to understand compression ratio... https://www.youtube.com/watch?v=nveqCMNTth0 Skimming is what you do to make the top of the block and head dead flat so they seal correctly. it is a cutting machine that takes tenth of a mm off the block or head each pass until it is flat. Most often done when you have blown a head gasket. Though closed decking, doweling and sleeves and head porting often requires it as well. Say you did this for a blown gasket for both head and block you have lost .4mm (2 passes at .1mm for head as well as block) then do it again for close deck or rebuilder does it out of habit you've lost 0.8mm from the above the piston. Now since this makes the cylinder shorter above the piston with the same crank stroke you increase the compression ratio as the cylinder volume is smaller but has the same stroke. Now compressing air weather by turbo or the piston in the cylinder creates heat (this is why intercooler are after the turbo and you need bigger coolers for higher power). if the heat gets too high the petrol and air detonate before the spark and since that is too early in the rotation of the crank it's not forcing the crank to turn as much as loading up the rod and bearings (which snaps the rods and makes holes in the block) Its like only peddling a bike when the pedal is vertical so you get less turning for the force you push downwards (almost no turning). Luckily on a bike the load is small and no damage happens. Now do that with a sledge hammer type force in and engine and you have a broken bike. That's why na Hondas are 11:1 and turbos are 9:1 (8.5:1 in 1990's) Hondas have no turbo heat so can compress the cylinder more before the detonation happens. Hope that S*** makes some sense it's long and I haven't checked it. Though someone will point out holes(pun) in it. ive ignored the good bits like: turbo efficiency maps/graphs which is where turbos compress air the most with the least heat. Over working a stocker of creates too much heat which is why you get a bigger one. Too big and it lags, too small it just heats the air. fuel quality i.e. Octane that resists destination or requires more heat to ignite. And the trade off between on and off boost performance/efficiency of compression ratios. @Inked in short as long as the heat is below the point that the fuel detonates you're good. So more efficient turbo and bigger cooler will allow you to get more power before things go wrong. that or thick arse head gasket to restore the missing height.
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@Gripless When my motor was built Chris told me that my head must of been skimmed down a bit as the compression was higher. I am not that motor savey would you be able to elaborate on this please? He told me that once I get bigger injectors,turbo etc we can go for more power but it was effecting the stock setup to try and squeeze more out of it. Is this a bad thing to have? will it mean that even once I gain a larger turbo than the VF30 and supporting mods that my motor may not handle the power. TIA (sorry to hijack thread @Subru)
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Mine doesn't use any oil, but my blowby ruffles your hair if you open the oil cap, and leaves a nasty film on the tmic. I hit 211kw at 400nm, couldn't add any more timing because of knock. Even if it was richened up, still knocked. Oil catch can (or air oil separator) and try again.
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150,000kms I have a oil catch can which I could install, this might give an indication of how much blowby is happening. Doesnt seem to use much oil either.
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@Subru what's your milage? Pull the tmic, check for a film of oil. Blowby will reduce your knock resistance quite a lot.
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Could be anything from previous head skimming upping compression etc. again compression test shows this. still could be wrong plugs or gap... its going to be annoying you for a few days so just enjoy the non detonating extra power, have a beer and chill until you get a few tests back. Good thing is you found an issue before the car went pop
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@Inked Yeah well at least its not knocking anymore too @Gripless yeah will do. Another thing to mention is that the first dyno in winter got 177kw and it was 6 degrees, today was 32 degrees inside the dyno area. Thats a big difference.
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Start with the compression test as that will tell you if it's a big job or not... If it comes back good straight away then you have less stress. At the same time: the plugs (colour and heat number) since they are out anyway for the compression test. piston tops for carbon build up. Again same time as compression test. then cheap easy stuff like: fuel pressure and quality timing, the physical base And intercooler is clean and free from oil and the fins aren't all bent. Unlikely but can cause a heat issue. Is the intake temp sensor high if you log it?
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Ahh that's all good man, even though it wasn't the numbers you are hoping atleast you have the piece of mind that Chris has got it to a point that is safe. When mine was tuned it had the same issue as well which is strange? He replaced my Cam angle sensor? by memory and it made it a lot better. at least the touch up tunes are like a quick $150 haha I have had a few
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Results are in... 190kw 365nm This really baffled Chris (tuner) and he suspects there could be engine issues or something. He was expecting 210 which are the results he usually gets with these. He said as soon as he put any timing in, it would detonate really bad. He suggested to get a compression check and leak down test (should have already done this duh...). He said it was running a bit lean so he cleaned the MAF sensor and it was a bit more rich but still not the usual rich he usually sees on Subarus and he wonders what damage could have been done due to being run lean for however long its been like it. Boost holds better than he expected going from 22.6psi and dropping to only 18-19ish so I suspect the turbo is okay. There was a black wrx that he also tuned today that went from 135kw to 180kw on 16psi but my car just didnt have it... So ima see whats wrong and then any changes I make will require touch ups and hopefully the engine is not fu**ed. lmk thoughts/ideas Edit: First dyno run in winter got 177kw and it was 6 degrees. Today was 32 degrees. If that makes any difference.
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Nope can do it on the ground, but yeah torque wrench helps. Or do everything up to FT (F*** tight) actually once the bar is undone you may want to jack the car up one side to get the bigger bar past the exhaust and over one arm (learnt this the hard swearing way). Doesn't matter which side. Then drop the car again to attach the end links. Adjustable bars are longer at the ends so can take a little more juggling to get in, than the old bar takes to get out. Not it a bad idea to pick up a brass bristled brush to clean the threads before you undo the factory stuff. Like $2-4 from warehouse/bunnings.
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Need ramps, a torque wrench and 30 minutes
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Now you just need 30 minutes to install it. Oh plus a full tank of gas and some clear roads to test it.
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